In order to satisfy requirements of users of radio cellular mobile networks for higher speed, broader coverage, and larger capacity, radio cellular mobile networks are evolving from the 3G. (3rd-generation, third generation mobile communication technologies) technologies to the LTE (Long Term Evolution, long term evolution) technology, and further to the LTE-Advanced (LTE-Advanced) technology.
The LTE technology supports fast scheduling and link adaptation technology for both uplink and downlink, and can allocate time-and-frequency resources according to an instantaneous requirement and a channel state of a user. In an uplink scheduling technology, because LTE can divide a frequency domain into a plurality of segments, LTE can schedule resources for multiple UEs simultaneously at a same subframe (subframe). In general, in order to extend a battery life of a UE and reduce intra-cell (Intra-cell) interference and inter-cell (Inter-cell) interference, transmit power of the UE should be not overused. In an LTE system, an eNodeB (evolved NodeB, evolved base station) is used to perform power control on UEs to achieve the above objective. The eNodeB adjusts the transmit power of a UE by sending a TPC Command (Transmission Power Control Command, transmit power control command). Based on the TPC Command sent by the eNodeB, the UE may adjust uplink transmit power in the following two modes: an accumulation (accumulation) mode and an absolute (absolute) mode. In the accumulation mode, the UE accumulates a value corresponding to each TPC (Transmission Power Control, transmit power control) received from the eNodeB, where an accumulative result is used to adjust the uplink transmit power. In the absolute mode, the UE directly uses a value corresponding to each TPC received from the eNodeB to adjust the uplink transmit power.
No matter whether in the accumulation mode or the absolute mode, the UE needs to set a PUSCH (Physical Uplink Control Channel, uplink data channel) initial power adjustment value fc(0) of and/or a PUCCH (Physical Uplink Shared Channel, uplink control channel) initial power adjustment value gc(0), and then obtains transmit power values based on PUSCH and PUCCH transmit power calculation formulas to set the uplink transmit power, thereby achieving power control. In the prior art, the setting of the initial power adjustment value depends on a type of a carrier configured by the eNodeB. If a carrier to be adjusted is a Pcell (Primary Carrier, primary carrier), using a PUSCH channel as an example, the UE sets the PUSCH channel initial power adjustment value of the Pcell to fc(0)=ΔPrampup+δmsg2, where δmsg2 is a power adjustment value represented by the TPC Command received by the UE, and ΔPrampup is a total power ramping value of the UE in an RA (Random Access, random access) process. For another Scell (Secondary Carrier, secondary carrier), the UE sets the PUSCH channel initial power adjustment value of the Scell to 0. Based on the initial power adjustment values set above, the eNodeB sends the TPC Command of the Scell to the UE by adopting power control which is the same as that for the Pcell channel based on adjustment of an uplink transmit power of the Pcell channel, to adjust uplink transmit power of the Scell channel, thereby achieving power control over the Scell channel. The eNodeB performs power control over the PUCCH channel of the Pcell and the Scell in a similar way.
The above solution in the prior art is only applicable to a situation where a difference between channel states of the Pcell and the Scell is small. However, in some scenarios, a difference between the channel states of the Pcell and the Scell may be large. For example, in an inter-band (Inter-Band) carrier aggregation scenario, a difference between PLs (Path Loss, path loss) of channels of the Pcell and the Scell is large. In this situation, if the initial power adjustment value of the Scell is still set to 0 according to the prior art, and on this basis, the eNodeB cannot accurately send a proper TPC Command to the Scell according to adjustment of the uplink transmit power of the Pcell channel to adjust the uplink transmit power of the Scell, which results in that the uplink transmit power of the UE on the Scell is excessively large or excessively small. If the uplink transmit power of the UE on the Scell is excessively large, power consumption of the UE is increased, and interference to surrounding UEs is also increased. If the uplink transmit power of the UE on the Scell is excessively small, a signal sent by the UE cannot be accurately parsed by the eNodeB, resulting in an extra data transmission delay, thereby wasting air interface resources. In view of the above, in a situation where the difference between the channel states of the Pcell and the Scell is large, how to perform appropriate power control over the Scell channel to enable the uplink transmit power of the UE on the Scell to have a proper value becomes an issue to be settled urgently.